INSTALLATION
   
 

A cooling air supply must be provided for transformers placed indoor or in a metal enclosure. 
A good ventilation system has to permit the entrance of fresh air from a "S" section placed on the base and the exit of warm air from "S" section placed on the top of the opposite side at "H" height from the entry.
   
 
FORMULA:

P = Transformer total losses (in kW) 
S = Entry surface (without possible grate) in sq. mt. 
S1 = Exit surface (without possible grate) in sq. mt. 
H = Distance between the two surface in mt. 
   
 
   
  If a sufficient cooling surface cannot be provided, it is necessary to employ a mechanical activated means of ventilation. 
The air flow should be 4.5 mc per minute for each kW loss which corresponds to an air temperature rise of  12° C approxymately. 
 
 
 

INSULATION DISTANCE 

For a proper transformer installation it is necessary to respect the values stated in the following table. 

   
 
 Insulation Class
Test voltage kV 
Wall of brieks 
Framework wall 
 kV
 50 Hz
1,2/50us 
mm 
mm 
7.2 
20 
60 
90 
300 
12 
28 
75 
120 
300 
17.5 
38 
95 
220 
300 
24 
50 
125 
220 
300 
36 
70 
170 
320 
320